enervent-ctrl

Enervent-control

External control of an Enervent Pingvin Kotilämpö residential heating/ventilation unit via RS485 bus using the Modbus protocol.

Provides a REST API for integration into Home Assistant, with measurements and basic control over Pingvin functions.

Template YAML configurations for Home Assistant are included in the homeassistant folder, intended to be simple to copy-paste into Home Assistant's configuration.yaml with minimal necessary modifications. These include sensor configurations, helpers and automations for button functions and a ready made basic dashboard. No custom components are necessary.

The daemon is designed to run on a Linux host that has some sort of RS-485 connector attached. For development a RPi Zero W 1 with a connected Zihatec RS 485 HAT has been used.

Building

• clone or download the repo
• static/html/index.html is symlinked to coils and registers for development purposes, the symlinks need to be dereferenced before building the binary on filesystems that support symlinks
  • Replace symlinks with copies of the files or use e.g. tar -h
• Build for the correct architecture, e.g. for Linux 32-bit ARM (Rpi Zero W 1):

  cd /path/to/repo
  env GOOS=linux GOARCH=arm go build -o BUILD/enervent-ctrl-linux-arm32
  

Configuration:

• CLI flags:

  -cert string
        Path to SSL public key to use for HTTPS (default "~/.config/enervent-ctrl/certificate.pem")
  -debug
        Enable debug logging
  -enable-metrics
        Enable the built-in Prometheus exporter (default true)
  -httplog
        Enable HTTP access logging
  -interval int
        Set the interval of background updates (default 4)
  -key string
        Path to SSL private key to use for HTTPS (default "~/.config/enervent-ctrl/privatekey.pem")
  -logfile string
        Path to log file. Default is empty string, log to stdout
  -password string
        Password for HTTP Basic Authentication (default "enervent")
  -regenerate-certs ~/.config/enervent-ctrl/server.crt
        Generate a new SSL certificate. A new one is generated on startup as ~/.config/enervent-ctrl/server.crt if it doesn't exist.
  -serial string
        Path to serial console for RS-485 connection. Defaults to /dev/ttyS0 (default "/dev/ttyS0")
  -username string
        Username for HTTP Basic Authentication (default "pingvin")

On first run, the daemon generates ~/.config/enervent-ctrl/configuration.yaml with default values. Configuration options are the same as with CLI flags. CLI flags take precedenence over the config file.

• serial_address: Path to RS-485 serial device
• port: TCP port for the REST API to listen on
• ssl_certificate: Path to SSL certificate for HTTPS
• ssl_privatekey: Path to SSL private key for HTTPS
• username: Username for REST API HTTP Basic Auth
• password: Password for REST API HTTP Basic Auth
• interval: Interval of background updates from Modbus
• enable_metrics: Enable the built-in Prometheus exporter
• log_file: Path to log file, default logging is to STDOUT
• log_access: Enable HTTP Access logging to logfile/STDOUT
• debug: Enable debug logging

Running

• Upload the built executable along with coils.csv and registers.csv to the target host. The files should be placed in the same folder.
• Run the binary as a regular user. Adding the user to the correct group for serial access may be necessary
• To run persistently, you can use screen, tmux, or generate a user systemd service unit file.
• Example systemd service file (named e.g. enervent-ctrl.service):

[Unit]
Description=Enervent-ctrl
After=network-online.target

[Service]
Type=simple
Restart=on-failure
RestartSec=30
ExecStart=/path/to/enervent-ctrl-executable

[Install]
WantedBy=default.target

• Replace paths in the file and place it under ~/.config/systemd/user. Create the folder if it doesn't exist.
• systemctl --user daemon-reload
• systemctl --user enable --now enervent-ctrl.service
• To let user services continue running after logging out:
  • sudo loginctl enable-linger $USER

Disclaimer:

I am not responsible of possible damage to your device if you choose to follow these instructions

The manufacturer may void your warranty if you choose to follow these instructions

Connecting to the Pingvin unit

RPi/computer running the daemon

• Connect an RS-485 adapter to the computer you intend to run the daemon on
  • Tested only on a RPi 4B and Zero W 1 with the Zihatec RS-485 HAT
  • You may need terminating resistors in your adapter, see documentation of your adapter.
• Ensure the user you intend to run the daemon as has read/write privileges to the serial device.
  • No need to run the daemon as root, and it is not recommended

Pingvin

• Shut down the main power of the unit
• Disconnect the device from mains, discharge any static electricity before proceeding
  • A new motherboard seems to cost close to 1000€ + labour
• Open the cover in which the power switch is attached to. No need to disconnect the switch, there should be enough length in the wires to move the lid with the switch connected out of the way
• Locate the green RS-485 connector on the motherboard, should be on the right edge
  • Schematics available from Enervent at https://doc.enervent.com/op/op.ViewOnline.php?documentid=940&version=1, page 38 (finnish)
• There should be available outlet holes to pass the wires through on the top of the electronics compartment.
• The connector has a detachable plug part. Grab the top of the connector (the part with the screws) with plyers and carefully pull it out. This will make attaching the wire much easier
• Attach wires by tightening the screws in the connector
• Connect A connector to A connector and B to B. (they are not Tx/Rx like in many other serials)
  • NOTE: After reading quite a few forum posts, many RS-485 adapters seem to have printed the A and B the wrong way, I wouldn't be surprised if this was the case with Pingvin too.
• Plug the plug back to the Pingvin motherboard and close the cover and screws
• Reconnect mains and switch both devices on
• Mixing A and B should be safe and won't break anything, but the daemon won't work. If that's the case, disconnect power again and switch the wires on the RPi end.

Home Assistant

• There are so many variations for HASS configs, that definite instructions are hard to do.
• All the YAMLs are intended to be copy-pasted to configuration.yaml (or files included to configuration.yaml)
• Change the IP address, port, username and password according to your configuration
• Restart Home Assistant (A full reload doesn't seem to be enough for all REST integration features to update)

Work is part of my Bachelor's Thesis at Oulu University of Applied Sciences.

Pingvin and Kotilämpö are registered trademarks of Enervent Zehnder Oy.